Art of manufacturing paraffin



Patented June 25, 1929.

UNITED STATES PATENT OFFICE.

CLARENCE A. WARD, or LINDEN, NEw JERSEY, ASSIGNOR T srANnAR-n OIL DE- VELOPMENT COMPANY, A CORPORATION or DELAWARE.

' -ART OF MANUFACTURING PARAFFIN.

No Drawing.

The present invention is directed to the art of treating a hydrocarbon distillate. The

' invention is particularly concerned with a process whereby a paraflin-containing petroleum fraction, from which paraflin is not normally directly obtained without other preliminary treatment, may be satisfactorily chilled and pressed, thereby yielding a resid-,

ual oil possessing high lubricating value while producing a slack wax which after treating can be readily finished into a paraf fin of commercial qualities. The invention will be understood from the following description,wherein the process claimed is fully set forth and described.

Crude petroleum oil is separated by distillation processes into a number of different cuts or fractions the particular process employed being dependent on a number of factors, such from the so-called parafiin distillate by the well-known process of pressing a suitably chilled distillate and sweating and treating the crude wax so obtained. Paraffin slop, however, which frequently contains a larger proportion of paraffin than does the paraffin distillate, cannot be treated in the same manner as the distillate mentioned for the recovery of paraflin therefrom. This is possibly due to the presence in the slop of heavy amorphous material of a petrolatum-like nature, .which renders a satisfactory sweating of a paraflin containing this material extremely diflicult and almost impossible to perform. For this reason, it has often been the practice to subject a parafiin slop to a further distillation step or rerunning in which considerable cracking occurs,'whereby a fraction having the characteristics of a paraffin distill- Application filed November 20, 1925. Serial No. 70,414.

down process, thereby producing comparatively large losses of valuable fractions, particularly of the lubricating oils present.

I have now found that a paraffin of good quality, accompanied with increased yields of oil by pressing, due in part to the smaller size of the particles of solidified paraflin in the chilled slop as well as to the presence of-amorphous bodies of a petrolatum-like nature, as pointed out above. It is, however, possible to realize a substantially complete'separation of the paraflin from the slop if the filter blankets used in the pressing operation be precoated preliminarily with a material that will reduce the porosity of the blankets and permit the ready removal of the slack wax from the blanket. This preliminary treatment of the filter blanket is Very necessary for the economical operation of my process. If a paraffin slop were passed through a press containing the ordinary uncoated filter plates, the pores would clog so completely that when the wax was removed therefrom the blanket could not be used again without a very complete and troublesome cleaning. By precoating the blanket as described, the slack wax deposited on pressing can be easily removed and the blanketleft clean and readily usable. Therefore, the canvas covered plates or blankets of the type commonly used in paraflin presses are first precoated with a filter ple a gravity of 276 B., a pour test of 60 and viscosity of 78 seconds Saybolt at F., was chilled to a temperature of about 2-l F. and passed through a press, the blankets of which had been first coated with a layer of good Wax in the manner as described. A slack wax was separated from the paraflin slop which was thereby deposited on the filter blankets, while the pressed oil, substantially freedof its paraffin content, was worked up into suitable lubricating oil fractions. The

. to the amount used inprecoating the filter slack wax deposited on the blankets could be removed readily therefrom in the usual manner, due to the layer of higher quality paraffin wax having been first deposited thereon, but the combined wax could not be treated in the usual manner by sweating as hereinbefore mentioned.

The slack wax, separated as described from the paraffin slop, was then distilled to coke, during which operation sufficient cracking was done to destroy partially the deleterious compounds, whereby an overhead distillate of approximately 9 to 95% by volume of the slack wax charged to the stills was obtained. This distillate was then chilled in the usual manner and pressed, and a slack wax having a melting point of approximately 109 F was obtained. This wax, being freed from the materials preventing sweating could now be directly sweated, and upon such treatment yielded a crude scale wax melting at about123 F.

My new process may likewise be used to treat a paraffin slop produced by other methods than that descrlbed. For example, a Mid- Continent crude oil may be reduced by fire and steam under atmospheric pressure to approximately a 50% bottom. These bottoms are then distilled under a 28 inch vacuum with steam, taking off a distillate up to approximately 56% of the oil charged, thus producing a good pressing paraffin distillate, while the cut from 56 to 83%, representing about 13.5% of the original crude oil and comprising a paraffin slop, was treated by my new process.

This slop was too viscous for easy handling on chilling and was therefore first thinned down with approximately one-fourth its volume of a lighter oil, such as a gas oil, and the mixture having a gravity of 28 B., pour test of 60 and Viscosity at 100 F. of 80 seconds Saybolt, was chilled and pressed on blankets precoated with a thin laver of ood quality paraffin wax as before. The slac wax so obtained was then distilled to coke, as in the pre vious example, and yielded 92.5%0f an overhead distillate which was then chilled, pressed and sweated, and produced a crude scale wax having a melting point of approximately 118 F. This wax could be readily treated and purified, and yielded a high grade commercial paraflin.

Similar fractions obtained from the distillation of other crude oils and prepared by any suitable distillation process may likewise be treated in the manner as set forth above. It is to be noted that not only do I obtain a considerable yield of paraffin wax in addition blankets, but what is even more important, by pressing the slop and recovering-lubricating oils from the pressed oil, I obtain a much greater yield of lubricants than is essible if all the slop is run to coke, as is one in ordinary practice. Although it is usually desirable to precoat the filter blankets as described, other means may be employed for accomplishing the result realized by this step. Thus, I may, preferably after chilling a paraffin slop distillate, add a quantity of clay or other free filtering medium thereto, with stirring, and then press the wax therefrom in the usual manner. The wax clay mixture may be redistilled, leaving the clay in the residue in the still. Substantially the same beneficial results are thereby obtained as are realized by using the precoated filter blanket as described.

The term slop or paraffin slop as used herein is employed in the sense and with the meaning as understood in oil refineries where the word designates any heavy distillate of petroleum containing paraffin wax which is not up to the quality of paraffin distillate and which is usually put aside for redistillation.

While in describing my invention I have referred to certain specific details, it will be understood that these are illustrative only and not limitative. Nor is my invention to be understood as dependent upon the accuracy of any theory or reason suggested to explain the advantageous results realized. On the contrary, the invention is to be regarded as limited only as defined in the following claims, in which it is my intention to claim all novelty inherent in my invention as broadly as is permissible in view of the prior art.

hat I claim is:

1. The process of treating paraffin slop which comprises chilling the paraffin slop, pressing the chilled slop in the presence of a filter aid to obtain a pressed oil and a difficultly .sweatable slack-wax and distilling said difficultly sweatable slack-wax under conditions of substantial cracking to produce a distillate of sweatable slack-wax.

2. The process of treating paraffin slop which comprises chilling said slop, mixing a free filtering medium with said chilled slop, pressing the slop and added filtering medium to obtain a pressed oil and a difiicultly sweatable slack-wax in admixture with the free filtering medium, said medium acting asa filter aid during the pressing, and distilling said diflicultly sweatable slack-wax with substantial cracking to produce a. distillate of sweatable slack-wax.

3. The process of treating paraffin slop which comprises chilling said slop, mixing clay with said chilled slop, pressing the mixture whereby the clay acts as a filter aid, thus obtaining a pressed oil and a difiicultly sweatable slack-wax inadmixture with clay, distilling the difiicultly sweatable slack-wax under conditions of substantial cracking to produce a distillate of sweatable slack-wax.

CLARENCE A. WARD. 

